So whenever I try to run a game, the sound is disturbingly choppy, and the fps is incredibly slow . I have no idea what plugins to use and what settings to set. And I really want to fix this without having to overclock anything or upgrade any hardware because that costs MONEY. So can someone give my a simple solution for this? I can't take it anymore

Whats your actual graphics card? looks like an nvidia - switch to the proprietary drivers. Go to the software settings (don't remember the actual name, the one where you can access ppas (Open software updates and click on settings) there should be a tab with "additional drivers" that should give you the option to switch to proprietary nvidia driver) also mupen64plus 2.1 doesn't exist, are you using the one provided in the repos?

Sorry, it says mupen64plus 2.0.0. I mixed up the m64py version with the mupen64plus version. I just looked up mupen64 on google, found a download for it on the software center:
Plugin-based Nintendo 64 emulator (transitional dummy package).
It says "NVIDIA Corporation: G96 [GeForce 9500 GT] as the card model, and on the bottom of that it says this device is using an alternate driver.
It says no proprietary drivers are in use, and there a lot of drivers to choose from. Can you tell me exactly how to switch to a proprietary driver?

And first of all, none of the drivers are recommended, and second, when I tried switching to a different driver, well...let's just say that it took around 45 minutes to get my computer booting properly again rather than just going into an eternal black screen